Toxicity and Repellent Activity of Hedychium flavum Rhizome Essential Oil and Major Constituents Against Stored Product Insects1

An essential oil extracted from the rhizome of wild ginger, Hedychium flavum Roxburgh (Zingiberaceae), was evaluated for its toxic and repellent activity against adults of the stored product pests Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), Lasioderma serricorne (F.) (Coleoptera: Anobiidae), and Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae). Gas chromatography–flame ionization detection and gas chromatography–mass spectrometry revealed 24 compounds that composed 90.52% of the constituents of the extracted oil. The main compounds identified were β-pinene (33.52%), linalool (15.56%), and 1,8-cineole (11.20%). These three compounds and the rhizome essential oil were further assayed for their contact toxicity, fumigant, and repellent properties against the three stored product pests. Contact toxicity bioassays determined median lethal dosages (LD50 values) of the essential oil as 22.3 µg/adult for T. castaneum, 11.3 µg/adult for L. serricorne, and 109.9 μg/cm2 for L. bostrychophila. Analysis of the fumigant toxicity bioassay established LC50 values of 15.6 mg/L air for T. castaneum and 7.6 mg/L air for L. serricorne. The rhizome essential oil had higher repellent activity against the three stored product pests. Our results indicate the potential of the essential oil from rhizomes of H. flavum and its three main components as potential botanical insecticides for management of stored product pests.